1 /* 2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com> 3 * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 * 9 * Standard functionality for the common clock API. See Documentation/clk.txt 10 */ 11 12 #include <linux/clk-private.h> 13 #include <linux/module.h> 14 #include <linux/mutex.h> 15 #include <linux/spinlock.h> 16 #include <linux/err.h> 17 #include <linux/list.h> 18 #include <linux/slab.h> 19 #include <linux/of.h> 20 #include <linux/device.h> 21 #include <linux/init.h> 22 #include <linux/sched.h> 23 24 #include "clk.h" 25 26 static DEFINE_SPINLOCK(enable_lock); 27 static DEFINE_MUTEX(prepare_lock); 28 29 static struct task_struct *prepare_owner; 30 static struct task_struct *enable_owner; 31 32 static int prepare_refcnt; 33 static int enable_refcnt; 34 35 static HLIST_HEAD(clk_root_list); 36 static HLIST_HEAD(clk_orphan_list); 37 static LIST_HEAD(clk_notifier_list); 38 39 /*** locking ***/ 40 static void clk_prepare_lock(void) 41 { 42 if (!mutex_trylock(&prepare_lock)) { 43 if (prepare_owner == current) { 44 prepare_refcnt++; 45 return; 46 } 47 mutex_lock(&prepare_lock); 48 } 49 WARN_ON_ONCE(prepare_owner != NULL); 50 WARN_ON_ONCE(prepare_refcnt != 0); 51 prepare_owner = current; 52 prepare_refcnt = 1; 53 } 54 55 static void clk_prepare_unlock(void) 56 { 57 WARN_ON_ONCE(prepare_owner != current); 58 WARN_ON_ONCE(prepare_refcnt == 0); 59 60 if (--prepare_refcnt) 61 return; 62 prepare_owner = NULL; 63 mutex_unlock(&prepare_lock); 64 } 65 66 static unsigned long clk_enable_lock(void) 67 { 68 unsigned long flags; 69 70 if (!spin_trylock_irqsave(&enable_lock, flags)) { 71 if (enable_owner == current) { 72 enable_refcnt++; 73 return flags; 74 } 75 spin_lock_irqsave(&enable_lock, flags); 76 } 77 WARN_ON_ONCE(enable_owner != NULL); 78 WARN_ON_ONCE(enable_refcnt != 0); 79 enable_owner = current; 80 enable_refcnt = 1; 81 return flags; 82 } 83 84 static void clk_enable_unlock(unsigned long flags) 85 { 86 WARN_ON_ONCE(enable_owner != current); 87 WARN_ON_ONCE(enable_refcnt == 0); 88 89 if (--enable_refcnt) 90 return; 91 enable_owner = NULL; 92 spin_unlock_irqrestore(&enable_lock, flags); 93 } 94 95 /*** debugfs support ***/ 96 97 #ifdef CONFIG_DEBUG_FS 98 #include <linux/debugfs.h> 99 100 static struct dentry *rootdir; 101 static struct dentry *orphandir; 102 static int inited = 0; 103 104 static void clk_summary_show_one(struct seq_file *s, struct clk *c, int level) 105 { 106 if (!c) 107 return; 108 109 seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu\n", 110 level * 3 + 1, "", 111 30 - level * 3, c->name, 112 c->enable_count, c->prepare_count, clk_get_rate(c), 113 clk_get_accuracy(c)); 114 } 115 116 static void clk_summary_show_subtree(struct seq_file *s, struct clk *c, 117 int level) 118 { 119 struct clk *child; 120 121 if (!c) 122 return; 123 124 clk_summary_show_one(s, c, level); 125 126 hlist_for_each_entry(child, &c->children, child_node) 127 clk_summary_show_subtree(s, child, level + 1); 128 } 129 130 static int clk_summary_show(struct seq_file *s, void *data) 131 { 132 struct clk *c; 133 134 seq_puts(s, " clock enable_cnt prepare_cnt rate accuracy\n"); 135 seq_puts(s, "--------------------------------------------------------------------------------\n"); 136 137 clk_prepare_lock(); 138 139 hlist_for_each_entry(c, &clk_root_list, child_node) 140 clk_summary_show_subtree(s, c, 0); 141 142 hlist_for_each_entry(c, &clk_orphan_list, child_node) 143 clk_summary_show_subtree(s, c, 0); 144 145 clk_prepare_unlock(); 146 147 return 0; 148 } 149 150 151 static int clk_summary_open(struct inode *inode, struct file *file) 152 { 153 return single_open(file, clk_summary_show, inode->i_private); 154 } 155 156 static const struct file_operations clk_summary_fops = { 157 .open = clk_summary_open, 158 .read = seq_read, 159 .llseek = seq_lseek, 160 .release = single_release, 161 }; 162 163 static void clk_dump_one(struct seq_file *s, struct clk *c, int level) 164 { 165 if (!c) 166 return; 167 168 seq_printf(s, "\"%s\": { ", c->name); 169 seq_printf(s, "\"enable_count\": %d,", c->enable_count); 170 seq_printf(s, "\"prepare_count\": %d,", c->prepare_count); 171 seq_printf(s, "\"rate\": %lu", clk_get_rate(c)); 172 seq_printf(s, "\"accuracy\": %lu", clk_get_accuracy(c)); 173 } 174 175 static void clk_dump_subtree(struct seq_file *s, struct clk *c, int level) 176 { 177 struct clk *child; 178 179 if (!c) 180 return; 181 182 clk_dump_one(s, c, level); 183 184 hlist_for_each_entry(child, &c->children, child_node) { 185 seq_printf(s, ","); 186 clk_dump_subtree(s, child, level + 1); 187 } 188 189 seq_printf(s, "}"); 190 } 191 192 static int clk_dump(struct seq_file *s, void *data) 193 { 194 struct clk *c; 195 bool first_node = true; 196 197 seq_printf(s, "{"); 198 199 clk_prepare_lock(); 200 201 hlist_for_each_entry(c, &clk_root_list, child_node) { 202 if (!first_node) 203 seq_printf(s, ","); 204 first_node = false; 205 clk_dump_subtree(s, c, 0); 206 } 207 208 hlist_for_each_entry(c, &clk_orphan_list, child_node) { 209 seq_printf(s, ","); 210 clk_dump_subtree(s, c, 0); 211 } 212 213 clk_prepare_unlock(); 214 215 seq_printf(s, "}"); 216 return 0; 217 } 218 219 220 static int clk_dump_open(struct inode *inode, struct file *file) 221 { 222 return single_open(file, clk_dump, inode->i_private); 223 } 224 225 static const struct file_operations clk_dump_fops = { 226 .open = clk_dump_open, 227 .read = seq_read, 228 .llseek = seq_lseek, 229 .release = single_release, 230 }; 231 232 /* caller must hold prepare_lock */ 233 static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry) 234 { 235 struct dentry *d; 236 int ret = -ENOMEM; 237 238 if (!clk || !pdentry) { 239 ret = -EINVAL; 240 goto out; 241 } 242 243 d = debugfs_create_dir(clk->name, pdentry); 244 if (!d) 245 goto out; 246 247 clk->dentry = d; 248 249 d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry, 250 (u32 *)&clk->rate); 251 if (!d) 252 goto err_out; 253 254 d = debugfs_create_u32("clk_accuracy", S_IRUGO, clk->dentry, 255 (u32 *)&clk->accuracy); 256 if (!d) 257 goto err_out; 258 259 d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry, 260 (u32 *)&clk->flags); 261 if (!d) 262 goto err_out; 263 264 d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry, 265 (u32 *)&clk->prepare_count); 266 if (!d) 267 goto err_out; 268 269 d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry, 270 (u32 *)&clk->enable_count); 271 if (!d) 272 goto err_out; 273 274 d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry, 275 (u32 *)&clk->notifier_count); 276 if (!d) 277 goto err_out; 278 279 if (clk->ops->debug_init) 280 if (clk->ops->debug_init(clk->hw, clk->dentry)) 281 goto err_out; 282 283 ret = 0; 284 goto out; 285 286 err_out: 287 debugfs_remove_recursive(clk->dentry); 288 clk->dentry = NULL; 289 out: 290 return ret; 291 } 292 293 /* caller must hold prepare_lock */ 294 static int clk_debug_create_subtree(struct clk *clk, struct dentry *pdentry) 295 { 296 struct clk *child; 297 int ret = -EINVAL;; 298 299 if (!clk || !pdentry) 300 goto out; 301 302 ret = clk_debug_create_one(clk, pdentry); 303 304 if (ret) 305 goto out; 306 307 hlist_for_each_entry(child, &clk->children, child_node) 308 clk_debug_create_subtree(child, clk->dentry); 309 310 ret = 0; 311 out: 312 return ret; 313 } 314 315 /** 316 * clk_debug_register - add a clk node to the debugfs clk tree 317 * @clk: the clk being added to the debugfs clk tree 318 * 319 * Dynamically adds a clk to the debugfs clk tree if debugfs has been 320 * initialized. Otherwise it bails out early since the debugfs clk tree 321 * will be created lazily by clk_debug_init as part of a late_initcall. 322 * 323 * Caller must hold prepare_lock. Only clk_init calls this function (so 324 * far) so this is taken care. 325 */ 326 static int clk_debug_register(struct clk *clk) 327 { 328 struct clk *parent; 329 struct dentry *pdentry; 330 int ret = 0; 331 332 if (!inited) 333 goto out; 334 335 parent = clk->parent; 336 337 /* 338 * Check to see if a clk is a root clk. Also check that it is 339 * safe to add this clk to debugfs 340 */ 341 if (!parent) 342 if (clk->flags & CLK_IS_ROOT) 343 pdentry = rootdir; 344 else 345 pdentry = orphandir; 346 else 347 if (parent->dentry) 348 pdentry = parent->dentry; 349 else 350 goto out; 351 352 ret = clk_debug_create_subtree(clk, pdentry); 353 354 out: 355 return ret; 356 } 357 358 /** 359 * clk_debug_unregister - remove a clk node from the debugfs clk tree 360 * @clk: the clk being removed from the debugfs clk tree 361 * 362 * Dynamically removes a clk and all it's children clk nodes from the 363 * debugfs clk tree if clk->dentry points to debugfs created by 364 * clk_debug_register in __clk_init. 365 * 366 * Caller must hold prepare_lock. 367 */ 368 static void clk_debug_unregister(struct clk *clk) 369 { 370 debugfs_remove_recursive(clk->dentry); 371 } 372 373 /** 374 * clk_debug_reparent - reparent clk node in the debugfs clk tree 375 * @clk: the clk being reparented 376 * @new_parent: the new clk parent, may be NULL 377 * 378 * Rename clk entry in the debugfs clk tree if debugfs has been 379 * initialized. Otherwise it bails out early since the debugfs clk tree 380 * will be created lazily by clk_debug_init as part of a late_initcall. 381 * 382 * Caller must hold prepare_lock. 383 */ 384 static void clk_debug_reparent(struct clk *clk, struct clk *new_parent) 385 { 386 struct dentry *d; 387 struct dentry *new_parent_d; 388 389 if (!inited) 390 return; 391 392 if (new_parent) 393 new_parent_d = new_parent->dentry; 394 else 395 new_parent_d = orphandir; 396 397 d = debugfs_rename(clk->dentry->d_parent, clk->dentry, 398 new_parent_d, clk->name); 399 if (d) 400 clk->dentry = d; 401 else 402 pr_debug("%s: failed to rename debugfs entry for %s\n", 403 __func__, clk->name); 404 } 405 406 /** 407 * clk_debug_init - lazily create the debugfs clk tree visualization 408 * 409 * clks are often initialized very early during boot before memory can 410 * be dynamically allocated and well before debugfs is setup. 411 * clk_debug_init walks the clk tree hierarchy while holding 412 * prepare_lock and creates the topology as part of a late_initcall, 413 * thus insuring that clks initialized very early will still be 414 * represented in the debugfs clk tree. This function should only be 415 * called once at boot-time, and all other clks added dynamically will 416 * be done so with clk_debug_register. 417 */ 418 static int __init clk_debug_init(void) 419 { 420 struct clk *clk; 421 struct dentry *d; 422 423 rootdir = debugfs_create_dir("clk", NULL); 424 425 if (!rootdir) 426 return -ENOMEM; 427 428 d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, NULL, 429 &clk_summary_fops); 430 if (!d) 431 return -ENOMEM; 432 433 d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, NULL, 434 &clk_dump_fops); 435 if (!d) 436 return -ENOMEM; 437 438 orphandir = debugfs_create_dir("orphans", rootdir); 439 440 if (!orphandir) 441 return -ENOMEM; 442 443 clk_prepare_lock(); 444 445 hlist_for_each_entry(clk, &clk_root_list, child_node) 446 clk_debug_create_subtree(clk, rootdir); 447 448 hlist_for_each_entry(clk, &clk_orphan_list, child_node) 449 clk_debug_create_subtree(clk, orphandir); 450 451 inited = 1; 452 453 clk_prepare_unlock(); 454 455 return 0; 456 } 457 late_initcall(clk_debug_init); 458 #else 459 static inline int clk_debug_register(struct clk *clk) { return 0; } 460 static inline void clk_debug_reparent(struct clk *clk, struct clk *new_parent) 461 { 462 } 463 static inline void clk_debug_unregister(struct clk *clk) 464 { 465 } 466 #endif 467 468 /* caller must hold prepare_lock */ 469 static void clk_unprepare_unused_subtree(struct clk *clk) 470 { 471 struct clk *child; 472 473 if (!clk) 474 return; 475 476 hlist_for_each_entry(child, &clk->children, child_node) 477 clk_unprepare_unused_subtree(child); 478 479 if (clk->prepare_count) 480 return; 481 482 if (clk->flags & CLK_IGNORE_UNUSED) 483 return; 484 485 if (__clk_is_prepared(clk)) { 486 if (clk->ops->unprepare_unused) 487 clk->ops->unprepare_unused(clk->hw); 488 else if (clk->ops->unprepare) 489 clk->ops->unprepare(clk->hw); 490 } 491 } 492 493 /* caller must hold prepare_lock */ 494 static void clk_disable_unused_subtree(struct clk *clk) 495 { 496 struct clk *child; 497 unsigned long flags; 498 499 if (!clk) 500 goto out; 501 502 hlist_for_each_entry(child, &clk->children, child_node) 503 clk_disable_unused_subtree(child); 504 505 flags = clk_enable_lock(); 506 507 if (clk->enable_count) 508 goto unlock_out; 509 510 if (clk->flags & CLK_IGNORE_UNUSED) 511 goto unlock_out; 512 513 /* 514 * some gate clocks have special needs during the disable-unused 515 * sequence. call .disable_unused if available, otherwise fall 516 * back to .disable 517 */ 518 if (__clk_is_enabled(clk)) { 519 if (clk->ops->disable_unused) 520 clk->ops->disable_unused(clk->hw); 521 else if (clk->ops->disable) 522 clk->ops->disable(clk->hw); 523 } 524 525 unlock_out: 526 clk_enable_unlock(flags); 527 528 out: 529 return; 530 } 531 532 static bool clk_ignore_unused; 533 static int __init clk_ignore_unused_setup(char *__unused) 534 { 535 clk_ignore_unused = true; 536 return 1; 537 } 538 __setup("clk_ignore_unused", clk_ignore_unused_setup); 539 540 static int clk_disable_unused(void) 541 { 542 struct clk *clk; 543 544 if (clk_ignore_unused) { 545 pr_warn("clk: Not disabling unused clocks\n"); 546 return 0; 547 } 548 549 clk_prepare_lock(); 550 551 hlist_for_each_entry(clk, &clk_root_list, child_node) 552 clk_disable_unused_subtree(clk); 553 554 hlist_for_each_entry(clk, &clk_orphan_list, child_node) 555 clk_disable_unused_subtree(clk); 556 557 hlist_for_each_entry(clk, &clk_root_list, child_node) 558 clk_unprepare_unused_subtree(clk); 559 560 hlist_for_each_entry(clk, &clk_orphan_list, child_node) 561 clk_unprepare_unused_subtree(clk); 562 563 clk_prepare_unlock(); 564 565 return 0; 566 } 567 late_initcall_sync(clk_disable_unused); 568 569 /*** helper functions ***/ 570 571 const char *__clk_get_name(struct clk *clk) 572 { 573 return !clk ? NULL : clk->name; 574 } 575 EXPORT_SYMBOL_GPL(__clk_get_name); 576 577 struct clk_hw *__clk_get_hw(struct clk *clk) 578 { 579 return !clk ? NULL : clk->hw; 580 } 581 EXPORT_SYMBOL_GPL(__clk_get_hw); 582 583 u8 __clk_get_num_parents(struct clk *clk) 584 { 585 return !clk ? 0 : clk->num_parents; 586 } 587 EXPORT_SYMBOL_GPL(__clk_get_num_parents); 588 589 struct clk *__clk_get_parent(struct clk *clk) 590 { 591 return !clk ? NULL : clk->parent; 592 } 593 EXPORT_SYMBOL_GPL(__clk_get_parent); 594 595 struct clk *clk_get_parent_by_index(struct clk *clk, u8 index) 596 { 597 if (!clk || index >= clk->num_parents) 598 return NULL; 599 else if (!clk->parents) 600 return __clk_lookup(clk->parent_names[index]); 601 else if (!clk->parents[index]) 602 return clk->parents[index] = 603 __clk_lookup(clk->parent_names[index]); 604 else 605 return clk->parents[index]; 606 } 607 EXPORT_SYMBOL_GPL(clk_get_parent_by_index); 608 609 unsigned int __clk_get_enable_count(struct clk *clk) 610 { 611 return !clk ? 0 : clk->enable_count; 612 } 613 614 unsigned int __clk_get_prepare_count(struct clk *clk) 615 { 616 return !clk ? 0 : clk->prepare_count; 617 } 618 619 unsigned long __clk_get_rate(struct clk *clk) 620 { 621 unsigned long ret; 622 623 if (!clk) { 624 ret = 0; 625 goto out; 626 } 627 628 ret = clk->rate; 629 630 if (clk->flags & CLK_IS_ROOT) 631 goto out; 632 633 if (!clk->parent) 634 ret = 0; 635 636 out: 637 return ret; 638 } 639 EXPORT_SYMBOL_GPL(__clk_get_rate); 640 641 unsigned long __clk_get_accuracy(struct clk *clk) 642 { 643 if (!clk) 644 return 0; 645 646 return clk->accuracy; 647 } 648 649 unsigned long __clk_get_flags(struct clk *clk) 650 { 651 return !clk ? 0 : clk->flags; 652 } 653 EXPORT_SYMBOL_GPL(__clk_get_flags); 654 655 bool __clk_is_prepared(struct clk *clk) 656 { 657 int ret; 658 659 if (!clk) 660 return false; 661 662 /* 663 * .is_prepared is optional for clocks that can prepare 664 * fall back to software usage counter if it is missing 665 */ 666 if (!clk->ops->is_prepared) { 667 ret = clk->prepare_count ? 1 : 0; 668 goto out; 669 } 670 671 ret = clk->ops->is_prepared(clk->hw); 672 out: 673 return !!ret; 674 } 675 676 bool __clk_is_enabled(struct clk *clk) 677 { 678 int ret; 679 680 if (!clk) 681 return false; 682 683 /* 684 * .is_enabled is only mandatory for clocks that gate 685 * fall back to software usage counter if .is_enabled is missing 686 */ 687 if (!clk->ops->is_enabled) { 688 ret = clk->enable_count ? 1 : 0; 689 goto out; 690 } 691 692 ret = clk->ops->is_enabled(clk->hw); 693 out: 694 return !!ret; 695 } 696 EXPORT_SYMBOL_GPL(__clk_is_enabled); 697 698 static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk) 699 { 700 struct clk *child; 701 struct clk *ret; 702 703 if (!strcmp(clk->name, name)) 704 return clk; 705 706 hlist_for_each_entry(child, &clk->children, child_node) { 707 ret = __clk_lookup_subtree(name, child); 708 if (ret) 709 return ret; 710 } 711 712 return NULL; 713 } 714 715 struct clk *__clk_lookup(const char *name) 716 { 717 struct clk *root_clk; 718 struct clk *ret; 719 720 if (!name) 721 return NULL; 722 723 /* search the 'proper' clk tree first */ 724 hlist_for_each_entry(root_clk, &clk_root_list, child_node) { 725 ret = __clk_lookup_subtree(name, root_clk); 726 if (ret) 727 return ret; 728 } 729 730 /* if not found, then search the orphan tree */ 731 hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) { 732 ret = __clk_lookup_subtree(name, root_clk); 733 if (ret) 734 return ret; 735 } 736 737 return NULL; 738 } 739 740 /* 741 * Helper for finding best parent to provide a given frequency. This can be used 742 * directly as a determine_rate callback (e.g. for a mux), or from a more 743 * complex clock that may combine a mux with other operations. 744 */ 745 long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate, 746 unsigned long *best_parent_rate, 747 struct clk **best_parent_p) 748 { 749 struct clk *clk = hw->clk, *parent, *best_parent = NULL; 750 int i, num_parents; 751 unsigned long parent_rate, best = 0; 752 753 /* if NO_REPARENT flag set, pass through to current parent */ 754 if (clk->flags & CLK_SET_RATE_NO_REPARENT) { 755 parent = clk->parent; 756 if (clk->flags & CLK_SET_RATE_PARENT) 757 best = __clk_round_rate(parent, rate); 758 else if (parent) 759 best = __clk_get_rate(parent); 760 else 761 best = __clk_get_rate(clk); 762 goto out; 763 } 764 765 /* find the parent that can provide the fastest rate <= rate */ 766 num_parents = clk->num_parents; 767 for (i = 0; i < num_parents; i++) { 768 parent = clk_get_parent_by_index(clk, i); 769 if (!parent) 770 continue; 771 if (clk->flags & CLK_SET_RATE_PARENT) 772 parent_rate = __clk_round_rate(parent, rate); 773 else 774 parent_rate = __clk_get_rate(parent); 775 if (parent_rate <= rate && parent_rate > best) { 776 best_parent = parent; 777 best = parent_rate; 778 } 779 } 780 781 out: 782 if (best_parent) 783 *best_parent_p = best_parent; 784 *best_parent_rate = best; 785 786 return best; 787 } 788 EXPORT_SYMBOL_GPL(__clk_mux_determine_rate); 789 790 /*** clk api ***/ 791 792 void __clk_unprepare(struct clk *clk) 793 { 794 if (!clk) 795 return; 796 797 if (WARN_ON(clk->prepare_count == 0)) 798 return; 799 800 if (--clk->prepare_count > 0) 801 return; 802 803 WARN_ON(clk->enable_count > 0); 804 805 if (clk->ops->unprepare) 806 clk->ops->unprepare(clk->hw); 807 808 __clk_unprepare(clk->parent); 809 } 810 811 /** 812 * clk_unprepare - undo preparation of a clock source 813 * @clk: the clk being unprepared 814 * 815 * clk_unprepare may sleep, which differentiates it from clk_disable. In a 816 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk 817 * if the operation may sleep. One example is a clk which is accessed over 818 * I2c. In the complex case a clk gate operation may require a fast and a slow 819 * part. It is this reason that clk_unprepare and clk_disable are not mutually 820 * exclusive. In fact clk_disable must be called before clk_unprepare. 821 */ 822 void clk_unprepare(struct clk *clk) 823 { 824 if (IS_ERR_OR_NULL(clk)) 825 return; 826 827 clk_prepare_lock(); 828 __clk_unprepare(clk); 829 clk_prepare_unlock(); 830 } 831 EXPORT_SYMBOL_GPL(clk_unprepare); 832 833 int __clk_prepare(struct clk *clk) 834 { 835 int ret = 0; 836 837 if (!clk) 838 return 0; 839 840 if (clk->prepare_count == 0) { 841 ret = __clk_prepare(clk->parent); 842 if (ret) 843 return ret; 844 845 if (clk->ops->prepare) { 846 ret = clk->ops->prepare(clk->hw); 847 if (ret) { 848 __clk_unprepare(clk->parent); 849 return ret; 850 } 851 } 852 } 853 854 clk->prepare_count++; 855 856 return 0; 857 } 858 859 /** 860 * clk_prepare - prepare a clock source 861 * @clk: the clk being prepared 862 * 863 * clk_prepare may sleep, which differentiates it from clk_enable. In a simple 864 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the 865 * operation may sleep. One example is a clk which is accessed over I2c. In 866 * the complex case a clk ungate operation may require a fast and a slow part. 867 * It is this reason that clk_prepare and clk_enable are not mutually 868 * exclusive. In fact clk_prepare must be called before clk_enable. 869 * Returns 0 on success, -EERROR otherwise. 870 */ 871 int clk_prepare(struct clk *clk) 872 { 873 int ret; 874 875 clk_prepare_lock(); 876 ret = __clk_prepare(clk); 877 clk_prepare_unlock(); 878 879 return ret; 880 } 881 EXPORT_SYMBOL_GPL(clk_prepare); 882 883 static void __clk_disable(struct clk *clk) 884 { 885 if (!clk) 886 return; 887 888 if (WARN_ON(clk->enable_count == 0)) 889 return; 890 891 if (--clk->enable_count > 0) 892 return; 893 894 if (clk->ops->disable) 895 clk->ops->disable(clk->hw); 896 897 __clk_disable(clk->parent); 898 } 899 900 /** 901 * clk_disable - gate a clock 902 * @clk: the clk being gated 903 * 904 * clk_disable must not sleep, which differentiates it from clk_unprepare. In 905 * a simple case, clk_disable can be used instead of clk_unprepare to gate a 906 * clk if the operation is fast and will never sleep. One example is a 907 * SoC-internal clk which is controlled via simple register writes. In the 908 * complex case a clk gate operation may require a fast and a slow part. It is 909 * this reason that clk_unprepare and clk_disable are not mutually exclusive. 910 * In fact clk_disable must be called before clk_unprepare. 911 */ 912 void clk_disable(struct clk *clk) 913 { 914 unsigned long flags; 915 916 if (IS_ERR_OR_NULL(clk)) 917 return; 918 919 flags = clk_enable_lock(); 920 __clk_disable(clk); 921 clk_enable_unlock(flags); 922 } 923 EXPORT_SYMBOL_GPL(clk_disable); 924 925 static int __clk_enable(struct clk *clk) 926 { 927 int ret = 0; 928 929 if (!clk) 930 return 0; 931 932 if (WARN_ON(clk->prepare_count == 0)) 933 return -ESHUTDOWN; 934 935 if (clk->enable_count == 0) { 936 ret = __clk_enable(clk->parent); 937 938 if (ret) 939 return ret; 940 941 if (clk->ops->enable) { 942 ret = clk->ops->enable(clk->hw); 943 if (ret) { 944 __clk_disable(clk->parent); 945 return ret; 946 } 947 } 948 } 949 950 clk->enable_count++; 951 return 0; 952 } 953 954 /** 955 * clk_enable - ungate a clock 956 * @clk: the clk being ungated 957 * 958 * clk_enable must not sleep, which differentiates it from clk_prepare. In a 959 * simple case, clk_enable can be used instead of clk_prepare to ungate a clk 960 * if the operation will never sleep. One example is a SoC-internal clk which 961 * is controlled via simple register writes. In the complex case a clk ungate 962 * operation may require a fast and a slow part. It is this reason that 963 * clk_enable and clk_prepare are not mutually exclusive. In fact clk_prepare 964 * must be called before clk_enable. Returns 0 on success, -EERROR 965 * otherwise. 966 */ 967 int clk_enable(struct clk *clk) 968 { 969 unsigned long flags; 970 int ret; 971 972 flags = clk_enable_lock(); 973 ret = __clk_enable(clk); 974 clk_enable_unlock(flags); 975 976 return ret; 977 } 978 EXPORT_SYMBOL_GPL(clk_enable); 979 980 /** 981 * __clk_round_rate - round the given rate for a clk 982 * @clk: round the rate of this clock 983 * @rate: the rate which is to be rounded 984 * 985 * Caller must hold prepare_lock. Useful for clk_ops such as .set_rate 986 */ 987 unsigned long __clk_round_rate(struct clk *clk, unsigned long rate) 988 { 989 unsigned long parent_rate = 0; 990 struct clk *parent; 991 992 if (!clk) 993 return 0; 994 995 parent = clk->parent; 996 if (parent) 997 parent_rate = parent->rate; 998 999 if (clk->ops->determine_rate) 1000 return clk->ops->determine_rate(clk->hw, rate, &parent_rate, 1001 &parent); 1002 else if (clk->ops->round_rate) 1003 return clk->ops->round_rate(clk->hw, rate, &parent_rate); 1004 else if (clk->flags & CLK_SET_RATE_PARENT) 1005 return __clk_round_rate(clk->parent, rate); 1006 else 1007 return clk->rate; 1008 } 1009 EXPORT_SYMBOL_GPL(__clk_round_rate); 1010 1011 /** 1012 * clk_round_rate - round the given rate for a clk 1013 * @clk: the clk for which we are rounding a rate 1014 * @rate: the rate which is to be rounded 1015 * 1016 * Takes in a rate as input and rounds it to a rate that the clk can actually 1017 * use which is then returned. If clk doesn't support round_rate operation 1018 * then the parent rate is returned. 1019 */ 1020 long clk_round_rate(struct clk *clk, unsigned long rate) 1021 { 1022 unsigned long ret; 1023 1024 clk_prepare_lock(); 1025 ret = __clk_round_rate(clk, rate); 1026 clk_prepare_unlock(); 1027 1028 return ret; 1029 } 1030 EXPORT_SYMBOL_GPL(clk_round_rate); 1031 1032 /** 1033 * __clk_notify - call clk notifier chain 1034 * @clk: struct clk * that is changing rate 1035 * @msg: clk notifier type (see include/linux/clk.h) 1036 * @old_rate: old clk rate 1037 * @new_rate: new clk rate 1038 * 1039 * Triggers a notifier call chain on the clk rate-change notification 1040 * for 'clk'. Passes a pointer to the struct clk and the previous 1041 * and current rates to the notifier callback. Intended to be called by 1042 * internal clock code only. Returns NOTIFY_DONE from the last driver 1043 * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if 1044 * a driver returns that. 1045 */ 1046 static int __clk_notify(struct clk *clk, unsigned long msg, 1047 unsigned long old_rate, unsigned long new_rate) 1048 { 1049 struct clk_notifier *cn; 1050 struct clk_notifier_data cnd; 1051 int ret = NOTIFY_DONE; 1052 1053 cnd.clk = clk; 1054 cnd.old_rate = old_rate; 1055 cnd.new_rate = new_rate; 1056 1057 list_for_each_entry(cn, &clk_notifier_list, node) { 1058 if (cn->clk == clk) { 1059 ret = srcu_notifier_call_chain(&cn->notifier_head, msg, 1060 &cnd); 1061 break; 1062 } 1063 } 1064 1065 return ret; 1066 } 1067 1068 /** 1069 * __clk_recalc_accuracies 1070 * @clk: first clk in the subtree 1071 * 1072 * Walks the subtree of clks starting with clk and recalculates accuracies as 1073 * it goes. Note that if a clk does not implement the .recalc_accuracy 1074 * callback then it is assumed that the clock will take on the accuracy of it's 1075 * parent. 1076 * 1077 * Caller must hold prepare_lock. 1078 */ 1079 static void __clk_recalc_accuracies(struct clk *clk) 1080 { 1081 unsigned long parent_accuracy = 0; 1082 struct clk *child; 1083 1084 if (clk->parent) 1085 parent_accuracy = clk->parent->accuracy; 1086 1087 if (clk->ops->recalc_accuracy) 1088 clk->accuracy = clk->ops->recalc_accuracy(clk->hw, 1089 parent_accuracy); 1090 else 1091 clk->accuracy = parent_accuracy; 1092 1093 hlist_for_each_entry(child, &clk->children, child_node) 1094 __clk_recalc_accuracies(child); 1095 } 1096 1097 /** 1098 * clk_get_accuracy - return the accuracy of clk 1099 * @clk: the clk whose accuracy is being returned 1100 * 1101 * Simply returns the cached accuracy of the clk, unless 1102 * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be 1103 * issued. 1104 * If clk is NULL then returns 0. 1105 */ 1106 long clk_get_accuracy(struct clk *clk) 1107 { 1108 unsigned long accuracy; 1109 1110 clk_prepare_lock(); 1111 if (clk && (clk->flags & CLK_GET_ACCURACY_NOCACHE)) 1112 __clk_recalc_accuracies(clk); 1113 1114 accuracy = __clk_get_accuracy(clk); 1115 clk_prepare_unlock(); 1116 1117 return accuracy; 1118 } 1119 EXPORT_SYMBOL_GPL(clk_get_accuracy); 1120 1121 static unsigned long clk_recalc(struct clk *clk, unsigned long parent_rate) 1122 { 1123 if (clk->ops->recalc_rate) 1124 return clk->ops->recalc_rate(clk->hw, parent_rate); 1125 return parent_rate; 1126 } 1127 1128 /** 1129 * __clk_recalc_rates 1130 * @clk: first clk in the subtree 1131 * @msg: notification type (see include/linux/clk.h) 1132 * 1133 * Walks the subtree of clks starting with clk and recalculates rates as it 1134 * goes. Note that if a clk does not implement the .recalc_rate callback then 1135 * it is assumed that the clock will take on the rate of its parent. 1136 * 1137 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification, 1138 * if necessary. 1139 * 1140 * Caller must hold prepare_lock. 1141 */ 1142 static void __clk_recalc_rates(struct clk *clk, unsigned long msg) 1143 { 1144 unsigned long old_rate; 1145 unsigned long parent_rate = 0; 1146 struct clk *child; 1147 1148 old_rate = clk->rate; 1149 1150 if (clk->parent) 1151 parent_rate = clk->parent->rate; 1152 1153 clk->rate = clk_recalc(clk, parent_rate); 1154 1155 /* 1156 * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE 1157 * & ABORT_RATE_CHANGE notifiers 1158 */ 1159 if (clk->notifier_count && msg) 1160 __clk_notify(clk, msg, old_rate, clk->rate); 1161 1162 hlist_for_each_entry(child, &clk->children, child_node) 1163 __clk_recalc_rates(child, msg); 1164 } 1165 1166 /** 1167 * clk_get_rate - return the rate of clk 1168 * @clk: the clk whose rate is being returned 1169 * 1170 * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag 1171 * is set, which means a recalc_rate will be issued. 1172 * If clk is NULL then returns 0. 1173 */ 1174 unsigned long clk_get_rate(struct clk *clk) 1175 { 1176 unsigned long rate; 1177 1178 clk_prepare_lock(); 1179 1180 if (clk && (clk->flags & CLK_GET_RATE_NOCACHE)) 1181 __clk_recalc_rates(clk, 0); 1182 1183 rate = __clk_get_rate(clk); 1184 clk_prepare_unlock(); 1185 1186 return rate; 1187 } 1188 EXPORT_SYMBOL_GPL(clk_get_rate); 1189 1190 static int clk_fetch_parent_index(struct clk *clk, struct clk *parent) 1191 { 1192 int i; 1193 1194 if (!clk->parents) { 1195 clk->parents = kcalloc(clk->num_parents, 1196 sizeof(struct clk *), GFP_KERNEL); 1197 if (!clk->parents) 1198 return -ENOMEM; 1199 } 1200 1201 /* 1202 * find index of new parent clock using cached parent ptrs, 1203 * or if not yet cached, use string name comparison and cache 1204 * them now to avoid future calls to __clk_lookup. 1205 */ 1206 for (i = 0; i < clk->num_parents; i++) { 1207 if (clk->parents[i] == parent) 1208 return i; 1209 1210 if (clk->parents[i]) 1211 continue; 1212 1213 if (!strcmp(clk->parent_names[i], parent->name)) { 1214 clk->parents[i] = __clk_lookup(parent->name); 1215 return i; 1216 } 1217 } 1218 1219 return -EINVAL; 1220 } 1221 1222 static void clk_reparent(struct clk *clk, struct clk *new_parent) 1223 { 1224 hlist_del(&clk->child_node); 1225 1226 if (new_parent) { 1227 /* avoid duplicate POST_RATE_CHANGE notifications */ 1228 if (new_parent->new_child == clk) 1229 new_parent->new_child = NULL; 1230 1231 hlist_add_head(&clk->child_node, &new_parent->children); 1232 } else { 1233 hlist_add_head(&clk->child_node, &clk_orphan_list); 1234 } 1235 1236 clk->parent = new_parent; 1237 } 1238 1239 static struct clk *__clk_set_parent_before(struct clk *clk, struct clk *parent) 1240 { 1241 unsigned long flags; 1242 struct clk *old_parent = clk->parent; 1243 1244 /* 1245 * Migrate prepare state between parents and prevent race with 1246 * clk_enable(). 1247 * 1248 * If the clock is not prepared, then a race with 1249 * clk_enable/disable() is impossible since we already have the 1250 * prepare lock (future calls to clk_enable() need to be preceded by 1251 * a clk_prepare()). 1252 * 1253 * If the clock is prepared, migrate the prepared state to the new 1254 * parent and also protect against a race with clk_enable() by 1255 * forcing the clock and the new parent on. This ensures that all 1256 * future calls to clk_enable() are practically NOPs with respect to 1257 * hardware and software states. 1258 * 1259 * See also: Comment for clk_set_parent() below. 1260 */ 1261 if (clk->prepare_count) { 1262 __clk_prepare(parent); 1263 clk_enable(parent); 1264 clk_enable(clk); 1265 } 1266 1267 /* update the clk tree topology */ 1268 flags = clk_enable_lock(); 1269 clk_reparent(clk, parent); 1270 clk_enable_unlock(flags); 1271 1272 return old_parent; 1273 } 1274 1275 static void __clk_set_parent_after(struct clk *clk, struct clk *parent, 1276 struct clk *old_parent) 1277 { 1278 /* 1279 * Finish the migration of prepare state and undo the changes done 1280 * for preventing a race with clk_enable(). 1281 */ 1282 if (clk->prepare_count) { 1283 clk_disable(clk); 1284 clk_disable(old_parent); 1285 __clk_unprepare(old_parent); 1286 } 1287 1288 /* update debugfs with new clk tree topology */ 1289 clk_debug_reparent(clk, parent); 1290 } 1291 1292 static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index) 1293 { 1294 unsigned long flags; 1295 int ret = 0; 1296 struct clk *old_parent; 1297 1298 old_parent = __clk_set_parent_before(clk, parent); 1299 1300 /* change clock input source */ 1301 if (parent && clk->ops->set_parent) 1302 ret = clk->ops->set_parent(clk->hw, p_index); 1303 1304 if (ret) { 1305 flags = clk_enable_lock(); 1306 clk_reparent(clk, old_parent); 1307 clk_enable_unlock(flags); 1308 1309 if (clk->prepare_count) { 1310 clk_disable(clk); 1311 clk_disable(parent); 1312 __clk_unprepare(parent); 1313 } 1314 return ret; 1315 } 1316 1317 __clk_set_parent_after(clk, parent, old_parent); 1318 1319 return 0; 1320 } 1321 1322 /** 1323 * __clk_speculate_rates 1324 * @clk: first clk in the subtree 1325 * @parent_rate: the "future" rate of clk's parent 1326 * 1327 * Walks the subtree of clks starting with clk, speculating rates as it 1328 * goes and firing off PRE_RATE_CHANGE notifications as necessary. 1329 * 1330 * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending 1331 * pre-rate change notifications and returns early if no clks in the 1332 * subtree have subscribed to the notifications. Note that if a clk does not 1333 * implement the .recalc_rate callback then it is assumed that the clock will 1334 * take on the rate of its parent. 1335 * 1336 * Caller must hold prepare_lock. 1337 */ 1338 static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate) 1339 { 1340 struct clk *child; 1341 unsigned long new_rate; 1342 int ret = NOTIFY_DONE; 1343 1344 new_rate = clk_recalc(clk, parent_rate); 1345 1346 /* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */ 1347 if (clk->notifier_count) 1348 ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate); 1349 1350 if (ret & NOTIFY_STOP_MASK) { 1351 pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n", 1352 __func__, clk->name, ret); 1353 goto out; 1354 } 1355 1356 hlist_for_each_entry(child, &clk->children, child_node) { 1357 ret = __clk_speculate_rates(child, new_rate); 1358 if (ret & NOTIFY_STOP_MASK) 1359 break; 1360 } 1361 1362 out: 1363 return ret; 1364 } 1365 1366 static void clk_calc_subtree(struct clk *clk, unsigned long new_rate, 1367 struct clk *new_parent, u8 p_index) 1368 { 1369 struct clk *child; 1370 1371 clk->new_rate = new_rate; 1372 clk->new_parent = new_parent; 1373 clk->new_parent_index = p_index; 1374 /* include clk in new parent's PRE_RATE_CHANGE notifications */ 1375 clk->new_child = NULL; 1376 if (new_parent && new_parent != clk->parent) 1377 new_parent->new_child = clk; 1378 1379 hlist_for_each_entry(child, &clk->children, child_node) { 1380 child->new_rate = clk_recalc(child, new_rate); 1381 clk_calc_subtree(child, child->new_rate, NULL, 0); 1382 } 1383 } 1384 1385 /* 1386 * calculate the new rates returning the topmost clock that has to be 1387 * changed. 1388 */ 1389 static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate) 1390 { 1391 struct clk *top = clk; 1392 struct clk *old_parent, *parent; 1393 unsigned long best_parent_rate = 0; 1394 unsigned long new_rate; 1395 int p_index = 0; 1396 1397 /* sanity */ 1398 if (IS_ERR_OR_NULL(clk)) 1399 return NULL; 1400 1401 /* save parent rate, if it exists */ 1402 parent = old_parent = clk->parent; 1403 if (parent) 1404 best_parent_rate = parent->rate; 1405 1406 /* find the closest rate and parent clk/rate */ 1407 if (clk->ops->determine_rate) { 1408 new_rate = clk->ops->determine_rate(clk->hw, rate, 1409 &best_parent_rate, 1410 &parent); 1411 } else if (clk->ops->round_rate) { 1412 new_rate = clk->ops->round_rate(clk->hw, rate, 1413 &best_parent_rate); 1414 } else if (!parent || !(clk->flags & CLK_SET_RATE_PARENT)) { 1415 /* pass-through clock without adjustable parent */ 1416 clk->new_rate = clk->rate; 1417 return NULL; 1418 } else { 1419 /* pass-through clock with adjustable parent */ 1420 top = clk_calc_new_rates(parent, rate); 1421 new_rate = parent->new_rate; 1422 goto out; 1423 } 1424 1425 /* some clocks must be gated to change parent */ 1426 if (parent != old_parent && 1427 (clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) { 1428 pr_debug("%s: %s not gated but wants to reparent\n", 1429 __func__, clk->name); 1430 return NULL; 1431 } 1432 1433 /* try finding the new parent index */ 1434 if (parent) { 1435 p_index = clk_fetch_parent_index(clk, parent); 1436 if (p_index < 0) { 1437 pr_debug("%s: clk %s can not be parent of clk %s\n", 1438 __func__, parent->name, clk->name); 1439 return NULL; 1440 } 1441 } 1442 1443 if ((clk->flags & CLK_SET_RATE_PARENT) && parent && 1444 best_parent_rate != parent->rate) 1445 top = clk_calc_new_rates(parent, best_parent_rate); 1446 1447 out: 1448 clk_calc_subtree(clk, new_rate, parent, p_index); 1449 1450 return top; 1451 } 1452 1453 /* 1454 * Notify about rate changes in a subtree. Always walk down the whole tree 1455 * so that in case of an error we can walk down the whole tree again and 1456 * abort the change. 1457 */ 1458 static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event) 1459 { 1460 struct clk *child, *tmp_clk, *fail_clk = NULL; 1461 int ret = NOTIFY_DONE; 1462 1463 if (clk->rate == clk->new_rate) 1464 return NULL; 1465 1466 if (clk->notifier_count) { 1467 ret = __clk_notify(clk, event, clk->rate, clk->new_rate); 1468 if (ret & NOTIFY_STOP_MASK) 1469 fail_clk = clk; 1470 } 1471 1472 hlist_for_each_entry(child, &clk->children, child_node) { 1473 /* Skip children who will be reparented to another clock */ 1474 if (child->new_parent && child->new_parent != clk) 1475 continue; 1476 tmp_clk = clk_propagate_rate_change(child, event); 1477 if (tmp_clk) 1478 fail_clk = tmp_clk; 1479 } 1480 1481 /* handle the new child who might not be in clk->children yet */ 1482 if (clk->new_child) { 1483 tmp_clk = clk_propagate_rate_change(clk->new_child, event); 1484 if (tmp_clk) 1485 fail_clk = tmp_clk; 1486 } 1487 1488 return fail_clk; 1489 } 1490 1491 /* 1492 * walk down a subtree and set the new rates notifying the rate 1493 * change on the way 1494 */ 1495 static void clk_change_rate(struct clk *clk) 1496 { 1497 struct clk *child; 1498 unsigned long old_rate; 1499 unsigned long best_parent_rate = 0; 1500 bool skip_set_rate = false; 1501 struct clk *old_parent; 1502 1503 old_rate = clk->rate; 1504 1505 if (clk->new_parent) 1506 best_parent_rate = clk->new_parent->rate; 1507 else if (clk->parent) 1508 best_parent_rate = clk->parent->rate; 1509 1510 if (clk->new_parent && clk->new_parent != clk->parent) { 1511 old_parent = __clk_set_parent_before(clk, clk->new_parent); 1512 1513 if (clk->ops->set_rate_and_parent) { 1514 skip_set_rate = true; 1515 clk->ops->set_rate_and_parent(clk->hw, clk->new_rate, 1516 best_parent_rate, 1517 clk->new_parent_index); 1518 } else if (clk->ops->set_parent) { 1519 clk->ops->set_parent(clk->hw, clk->new_parent_index); 1520 } 1521 1522 __clk_set_parent_after(clk, clk->new_parent, old_parent); 1523 } 1524 1525 if (!skip_set_rate && clk->ops->set_rate) 1526 clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate); 1527 1528 clk->rate = clk_recalc(clk, best_parent_rate); 1529 1530 if (clk->notifier_count && old_rate != clk->rate) 1531 __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate); 1532 1533 hlist_for_each_entry(child, &clk->children, child_node) { 1534 /* Skip children who will be reparented to another clock */ 1535 if (child->new_parent && child->new_parent != clk) 1536 continue; 1537 clk_change_rate(child); 1538 } 1539 1540 /* handle the new child who might not be in clk->children yet */ 1541 if (clk->new_child) 1542 clk_change_rate(clk->new_child); 1543 } 1544 1545 /** 1546 * clk_set_rate - specify a new rate for clk 1547 * @clk: the clk whose rate is being changed 1548 * @rate: the new rate for clk 1549 * 1550 * In the simplest case clk_set_rate will only adjust the rate of clk. 1551 * 1552 * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to 1553 * propagate up to clk's parent; whether or not this happens depends on the 1554 * outcome of clk's .round_rate implementation. If *parent_rate is unchanged 1555 * after calling .round_rate then upstream parent propagation is ignored. If 1556 * *parent_rate comes back with a new rate for clk's parent then we propagate 1557 * up to clk's parent and set its rate. Upward propagation will continue 1558 * until either a clk does not support the CLK_SET_RATE_PARENT flag or 1559 * .round_rate stops requesting changes to clk's parent_rate. 1560 * 1561 * Rate changes are accomplished via tree traversal that also recalculates the 1562 * rates for the clocks and fires off POST_RATE_CHANGE notifiers. 1563 * 1564 * Returns 0 on success, -EERROR otherwise. 1565 */ 1566 int clk_set_rate(struct clk *clk, unsigned long rate) 1567 { 1568 struct clk *top, *fail_clk; 1569 int ret = 0; 1570 1571 if (!clk) 1572 return 0; 1573 1574 /* prevent racing with updates to the clock topology */ 1575 clk_prepare_lock(); 1576 1577 /* bail early if nothing to do */ 1578 if (rate == clk_get_rate(clk)) 1579 goto out; 1580 1581 if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) { 1582 ret = -EBUSY; 1583 goto out; 1584 } 1585 1586 /* calculate new rates and get the topmost changed clock */ 1587 top = clk_calc_new_rates(clk, rate); 1588 if (!top) { 1589 ret = -EINVAL; 1590 goto out; 1591 } 1592 1593 /* notify that we are about to change rates */ 1594 fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE); 1595 if (fail_clk) { 1596 pr_debug("%s: failed to set %s rate\n", __func__, 1597 fail_clk->name); 1598 clk_propagate_rate_change(top, ABORT_RATE_CHANGE); 1599 ret = -EBUSY; 1600 goto out; 1601 } 1602 1603 /* change the rates */ 1604 clk_change_rate(top); 1605 1606 out: 1607 clk_prepare_unlock(); 1608 1609 return ret; 1610 } 1611 EXPORT_SYMBOL_GPL(clk_set_rate); 1612 1613 /** 1614 * clk_get_parent - return the parent of a clk 1615 * @clk: the clk whose parent gets returned 1616 * 1617 * Simply returns clk->parent. Returns NULL if clk is NULL. 1618 */ 1619 struct clk *clk_get_parent(struct clk *clk) 1620 { 1621 struct clk *parent; 1622 1623 clk_prepare_lock(); 1624 parent = __clk_get_parent(clk); 1625 clk_prepare_unlock(); 1626 1627 return parent; 1628 } 1629 EXPORT_SYMBOL_GPL(clk_get_parent); 1630 1631 /* 1632 * .get_parent is mandatory for clocks with multiple possible parents. It is 1633 * optional for single-parent clocks. Always call .get_parent if it is 1634 * available and WARN if it is missing for multi-parent clocks. 1635 * 1636 * For single-parent clocks without .get_parent, first check to see if the 1637 * .parents array exists, and if so use it to avoid an expensive tree 1638 * traversal. If .parents does not exist then walk the tree with __clk_lookup. 1639 */ 1640 static struct clk *__clk_init_parent(struct clk *clk) 1641 { 1642 struct clk *ret = NULL; 1643 u8 index; 1644 1645 /* handle the trivial cases */ 1646 1647 if (!clk->num_parents) 1648 goto out; 1649 1650 if (clk->num_parents == 1) { 1651 if (IS_ERR_OR_NULL(clk->parent)) 1652 ret = clk->parent = __clk_lookup(clk->parent_names[0]); 1653 ret = clk->parent; 1654 goto out; 1655 } 1656 1657 if (!clk->ops->get_parent) { 1658 WARN(!clk->ops->get_parent, 1659 "%s: multi-parent clocks must implement .get_parent\n", 1660 __func__); 1661 goto out; 1662 }; 1663 1664 /* 1665 * Do our best to cache parent clocks in clk->parents. This prevents 1666 * unnecessary and expensive calls to __clk_lookup. We don't set 1667 * clk->parent here; that is done by the calling function 1668 */ 1669 1670 index = clk->ops->get_parent(clk->hw); 1671 1672 if (!clk->parents) 1673 clk->parents = 1674 kcalloc(clk->num_parents, sizeof(struct clk *), 1675 GFP_KERNEL); 1676 1677 ret = clk_get_parent_by_index(clk, index); 1678 1679 out: 1680 return ret; 1681 } 1682 1683 void __clk_reparent(struct clk *clk, struct clk *new_parent) 1684 { 1685 clk_reparent(clk, new_parent); 1686 clk_debug_reparent(clk, new_parent); 1687 __clk_recalc_accuracies(clk); 1688 __clk_recalc_rates(clk, POST_RATE_CHANGE); 1689 } 1690 1691 /** 1692 * clk_set_parent - switch the parent of a mux clk 1693 * @clk: the mux clk whose input we are switching 1694 * @parent: the new input to clk 1695 * 1696 * Re-parent clk to use parent as its new input source. If clk is in 1697 * prepared state, the clk will get enabled for the duration of this call. If 1698 * that's not acceptable for a specific clk (Eg: the consumer can't handle 1699 * that, the reparenting is glitchy in hardware, etc), use the 1700 * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared. 1701 * 1702 * After successfully changing clk's parent clk_set_parent will update the 1703 * clk topology, sysfs topology and propagate rate recalculation via 1704 * __clk_recalc_rates. 1705 * 1706 * Returns 0 on success, -EERROR otherwise. 1707 */ 1708 int clk_set_parent(struct clk *clk, struct clk *parent) 1709 { 1710 int ret = 0; 1711 int p_index = 0; 1712 unsigned long p_rate = 0; 1713 1714 if (!clk) 1715 return 0; 1716 1717 /* verify ops for for multi-parent clks */ 1718 if ((clk->num_parents > 1) && (!clk->ops->set_parent)) 1719 return -ENOSYS; 1720 1721 /* prevent racing with updates to the clock topology */ 1722 clk_prepare_lock(); 1723 1724 if (clk->parent == parent) 1725 goto out; 1726 1727 /* check that we are allowed to re-parent if the clock is in use */ 1728 if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) { 1729 ret = -EBUSY; 1730 goto out; 1731 } 1732 1733 /* try finding the new parent index */ 1734 if (parent) { 1735 p_index = clk_fetch_parent_index(clk, parent); 1736 p_rate = parent->rate; 1737 if (p_index < 0) { 1738 pr_debug("%s: clk %s can not be parent of clk %s\n", 1739 __func__, parent->name, clk->name); 1740 ret = p_index; 1741 goto out; 1742 } 1743 } 1744 1745 /* propagate PRE_RATE_CHANGE notifications */ 1746 ret = __clk_speculate_rates(clk, p_rate); 1747 1748 /* abort if a driver objects */ 1749 if (ret & NOTIFY_STOP_MASK) 1750 goto out; 1751 1752 /* do the re-parent */ 1753 ret = __clk_set_parent(clk, parent, p_index); 1754 1755 /* propagate rate an accuracy recalculation accordingly */ 1756 if (ret) { 1757 __clk_recalc_rates(clk, ABORT_RATE_CHANGE); 1758 } else { 1759 __clk_recalc_rates(clk, POST_RATE_CHANGE); 1760 __clk_recalc_accuracies(clk); 1761 } 1762 1763 out: 1764 clk_prepare_unlock(); 1765 1766 return ret; 1767 } 1768 EXPORT_SYMBOL_GPL(clk_set_parent); 1769 1770 /** 1771 * __clk_init - initialize the data structures in a struct clk 1772 * @dev: device initializing this clk, placeholder for now 1773 * @clk: clk being initialized 1774 * 1775 * Initializes the lists in struct clk, queries the hardware for the 1776 * parent and rate and sets them both. 1777 */ 1778 int __clk_init(struct device *dev, struct clk *clk) 1779 { 1780 int i, ret = 0; 1781 struct clk *orphan; 1782 struct hlist_node *tmp2; 1783 1784 if (!clk) 1785 return -EINVAL; 1786 1787 clk_prepare_lock(); 1788 1789 /* check to see if a clock with this name is already registered */ 1790 if (__clk_lookup(clk->name)) { 1791 pr_debug("%s: clk %s already initialized\n", 1792 __func__, clk->name); 1793 ret = -EEXIST; 1794 goto out; 1795 } 1796 1797 /* check that clk_ops are sane. See Documentation/clk.txt */ 1798 if (clk->ops->set_rate && 1799 !((clk->ops->round_rate || clk->ops->determine_rate) && 1800 clk->ops->recalc_rate)) { 1801 pr_warning("%s: %s must implement .round_rate or .determine_rate in addition to .recalc_rate\n", 1802 __func__, clk->name); 1803 ret = -EINVAL; 1804 goto out; 1805 } 1806 1807 if (clk->ops->set_parent && !clk->ops->get_parent) { 1808 pr_warning("%s: %s must implement .get_parent & .set_parent\n", 1809 __func__, clk->name); 1810 ret = -EINVAL; 1811 goto out; 1812 } 1813 1814 if (clk->ops->set_rate_and_parent && 1815 !(clk->ops->set_parent && clk->ops->set_rate)) { 1816 pr_warn("%s: %s must implement .set_parent & .set_rate\n", 1817 __func__, clk->name); 1818 ret = -EINVAL; 1819 goto out; 1820 } 1821 1822 /* throw a WARN if any entries in parent_names are NULL */ 1823 for (i = 0; i < clk->num_parents; i++) 1824 WARN(!clk->parent_names[i], 1825 "%s: invalid NULL in %s's .parent_names\n", 1826 __func__, clk->name); 1827 1828 /* 1829 * Allocate an array of struct clk *'s to avoid unnecessary string 1830 * look-ups of clk's possible parents. This can fail for clocks passed 1831 * in to clk_init during early boot; thus any access to clk->parents[] 1832 * must always check for a NULL pointer and try to populate it if 1833 * necessary. 1834 * 1835 * If clk->parents is not NULL we skip this entire block. This allows 1836 * for clock drivers to statically initialize clk->parents. 1837 */ 1838 if (clk->num_parents > 1 && !clk->parents) { 1839 clk->parents = kcalloc(clk->num_parents, sizeof(struct clk *), 1840 GFP_KERNEL); 1841 /* 1842 * __clk_lookup returns NULL for parents that have not been 1843 * clk_init'd; thus any access to clk->parents[] must check 1844 * for a NULL pointer. We can always perform lazy lookups for 1845 * missing parents later on. 1846 */ 1847 if (clk->parents) 1848 for (i = 0; i < clk->num_parents; i++) 1849 clk->parents[i] = 1850 __clk_lookup(clk->parent_names[i]); 1851 } 1852 1853 clk->parent = __clk_init_parent(clk); 1854 1855 /* 1856 * Populate clk->parent if parent has already been __clk_init'd. If 1857 * parent has not yet been __clk_init'd then place clk in the orphan 1858 * list. If clk has set the CLK_IS_ROOT flag then place it in the root 1859 * clk list. 1860 * 1861 * Every time a new clk is clk_init'd then we walk the list of orphan 1862 * clocks and re-parent any that are children of the clock currently 1863 * being clk_init'd. 1864 */ 1865 if (clk->parent) 1866 hlist_add_head(&clk->child_node, 1867 &clk->parent->children); 1868 else if (clk->flags & CLK_IS_ROOT) 1869 hlist_add_head(&clk->child_node, &clk_root_list); 1870 else 1871 hlist_add_head(&clk->child_node, &clk_orphan_list); 1872 1873 /* 1874 * Set clk's accuracy. The preferred method is to use 1875 * .recalc_accuracy. For simple clocks and lazy developers the default 1876 * fallback is to use the parent's accuracy. If a clock doesn't have a 1877 * parent (or is orphaned) then accuracy is set to zero (perfect 1878 * clock). 1879 */ 1880 if (clk->ops->recalc_accuracy) 1881 clk->accuracy = clk->ops->recalc_accuracy(clk->hw, 1882 __clk_get_accuracy(clk->parent)); 1883 else if (clk->parent) 1884 clk->accuracy = clk->parent->accuracy; 1885 else 1886 clk->accuracy = 0; 1887 1888 /* 1889 * Set clk's rate. The preferred method is to use .recalc_rate. For 1890 * simple clocks and lazy developers the default fallback is to use the 1891 * parent's rate. If a clock doesn't have a parent (or is orphaned) 1892 * then rate is set to zero. 1893 */ 1894 if (clk->ops->recalc_rate) 1895 clk->rate = clk->ops->recalc_rate(clk->hw, 1896 __clk_get_rate(clk->parent)); 1897 else if (clk->parent) 1898 clk->rate = clk->parent->rate; 1899 else 1900 clk->rate = 0; 1901 1902 clk_debug_register(clk); 1903 /* 1904 * walk the list of orphan clocks and reparent any that are children of 1905 * this clock 1906 */ 1907 hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) { 1908 if (orphan->num_parents && orphan->ops->get_parent) { 1909 i = orphan->ops->get_parent(orphan->hw); 1910 if (!strcmp(clk->name, orphan->parent_names[i])) 1911 __clk_reparent(orphan, clk); 1912 continue; 1913 } 1914 1915 for (i = 0; i < orphan->num_parents; i++) 1916 if (!strcmp(clk->name, orphan->parent_names[i])) { 1917 __clk_reparent(orphan, clk); 1918 break; 1919 } 1920 } 1921 1922 /* 1923 * optional platform-specific magic 1924 * 1925 * The .init callback is not used by any of the basic clock types, but 1926 * exists for weird hardware that must perform initialization magic. 1927 * Please consider other ways of solving initialization problems before 1928 * using this callback, as its use is discouraged. 1929 */ 1930 if (clk->ops->init) 1931 clk->ops->init(clk->hw); 1932 1933 kref_init(&clk->ref); 1934 out: 1935 clk_prepare_unlock(); 1936 1937 return ret; 1938 } 1939 1940 /** 1941 * __clk_register - register a clock and return a cookie. 1942 * 1943 * Same as clk_register, except that the .clk field inside hw shall point to a 1944 * preallocated (generally statically allocated) struct clk. None of the fields 1945 * of the struct clk need to be initialized. 1946 * 1947 * The data pointed to by .init and .clk field shall NOT be marked as init 1948 * data. 1949 * 1950 * __clk_register is only exposed via clk-private.h and is intended for use with 1951 * very large numbers of clocks that need to be statically initialized. It is 1952 * a layering violation to include clk-private.h from any code which implements 1953 * a clock's .ops; as such any statically initialized clock data MUST be in a 1954 * separate C file from the logic that implements its operations. Returns 0 1955 * on success, otherwise an error code. 1956 */ 1957 struct clk *__clk_register(struct device *dev, struct clk_hw *hw) 1958 { 1959 int ret; 1960 struct clk *clk; 1961 1962 clk = hw->clk; 1963 clk->name = hw->init->name; 1964 clk->ops = hw->init->ops; 1965 clk->hw = hw; 1966 clk->flags = hw->init->flags; 1967 clk->parent_names = hw->init->parent_names; 1968 clk->num_parents = hw->init->num_parents; 1969 if (dev && dev->driver) 1970 clk->owner = dev->driver->owner; 1971 else 1972 clk->owner = NULL; 1973 1974 ret = __clk_init(dev, clk); 1975 if (ret) 1976 return ERR_PTR(ret); 1977 1978 return clk; 1979 } 1980 EXPORT_SYMBOL_GPL(__clk_register); 1981 1982 /** 1983 * clk_register - allocate a new clock, register it and return an opaque cookie 1984 * @dev: device that is registering this clock 1985 * @hw: link to hardware-specific clock data 1986 * 1987 * clk_register is the primary interface for populating the clock tree with new 1988 * clock nodes. It returns a pointer to the newly allocated struct clk which 1989 * cannot be dereferenced by driver code but may be used in conjuction with the 1990 * rest of the clock API. In the event of an error clk_register will return an 1991 * error code; drivers must test for an error code after calling clk_register. 1992 */ 1993 struct clk *clk_register(struct device *dev, struct clk_hw *hw) 1994 { 1995 int i, ret; 1996 struct clk *clk; 1997 1998 clk = kzalloc(sizeof(*clk), GFP_KERNEL); 1999 if (!clk) { 2000 pr_err("%s: could not allocate clk\n", __func__); 2001 ret = -ENOMEM; 2002 goto fail_out; 2003 } 2004 2005 clk->name = kstrdup(hw->init->name, GFP_KERNEL); 2006 if (!clk->name) { 2007 pr_err("%s: could not allocate clk->name\n", __func__); 2008 ret = -ENOMEM; 2009 goto fail_name; 2010 } 2011 clk->ops = hw->init->ops; 2012 if (dev && dev->driver) 2013 clk->owner = dev->driver->owner; 2014 clk->hw = hw; 2015 clk->flags = hw->init->flags; 2016 clk->num_parents = hw->init->num_parents; 2017 hw->clk = clk; 2018 2019 /* allocate local copy in case parent_names is __initdata */ 2020 clk->parent_names = kcalloc(clk->num_parents, sizeof(char *), 2021 GFP_KERNEL); 2022 2023 if (!clk->parent_names) { 2024 pr_err("%s: could not allocate clk->parent_names\n", __func__); 2025 ret = -ENOMEM; 2026 goto fail_parent_names; 2027 } 2028 2029 2030 /* copy each string name in case parent_names is __initdata */ 2031 for (i = 0; i < clk->num_parents; i++) { 2032 clk->parent_names[i] = kstrdup(hw->init->parent_names[i], 2033 GFP_KERNEL); 2034 if (!clk->parent_names[i]) { 2035 pr_err("%s: could not copy parent_names\n", __func__); 2036 ret = -ENOMEM; 2037 goto fail_parent_names_copy; 2038 } 2039 } 2040 2041 ret = __clk_init(dev, clk); 2042 if (!ret) 2043 return clk; 2044 2045 fail_parent_names_copy: 2046 while (--i >= 0) 2047 kfree(clk->parent_names[i]); 2048 kfree(clk->parent_names); 2049 fail_parent_names: 2050 kfree(clk->name); 2051 fail_name: 2052 kfree(clk); 2053 fail_out: 2054 return ERR_PTR(ret); 2055 } 2056 EXPORT_SYMBOL_GPL(clk_register); 2057 2058 /* 2059 * Free memory allocated for a clock. 2060 * Caller must hold prepare_lock. 2061 */ 2062 static void __clk_release(struct kref *ref) 2063 { 2064 struct clk *clk = container_of(ref, struct clk, ref); 2065 int i = clk->num_parents; 2066 2067 kfree(clk->parents); 2068 while (--i >= 0) 2069 kfree(clk->parent_names[i]); 2070 2071 kfree(clk->parent_names); 2072 kfree(clk->name); 2073 kfree(clk); 2074 } 2075 2076 /* 2077 * Empty clk_ops for unregistered clocks. These are used temporarily 2078 * after clk_unregister() was called on a clock and until last clock 2079 * consumer calls clk_put() and the struct clk object is freed. 2080 */ 2081 static int clk_nodrv_prepare_enable(struct clk_hw *hw) 2082 { 2083 return -ENXIO; 2084 } 2085 2086 static void clk_nodrv_disable_unprepare(struct clk_hw *hw) 2087 { 2088 WARN_ON_ONCE(1); 2089 } 2090 2091 static int clk_nodrv_set_rate(struct clk_hw *hw, unsigned long rate, 2092 unsigned long parent_rate) 2093 { 2094 return -ENXIO; 2095 } 2096 2097 static int clk_nodrv_set_parent(struct clk_hw *hw, u8 index) 2098 { 2099 return -ENXIO; 2100 } 2101 2102 static const struct clk_ops clk_nodrv_ops = { 2103 .enable = clk_nodrv_prepare_enable, 2104 .disable = clk_nodrv_disable_unprepare, 2105 .prepare = clk_nodrv_prepare_enable, 2106 .unprepare = clk_nodrv_disable_unprepare, 2107 .set_rate = clk_nodrv_set_rate, 2108 .set_parent = clk_nodrv_set_parent, 2109 }; 2110 2111 /** 2112 * clk_unregister - unregister a currently registered clock 2113 * @clk: clock to unregister 2114 */ 2115 void clk_unregister(struct clk *clk) 2116 { 2117 unsigned long flags; 2118 2119 if (!clk || WARN_ON_ONCE(IS_ERR(clk))) 2120 return; 2121 2122 clk_prepare_lock(); 2123 2124 if (clk->ops == &clk_nodrv_ops) { 2125 pr_err("%s: unregistered clock: %s\n", __func__, clk->name); 2126 goto out; 2127 } 2128 /* 2129 * Assign empty clock ops for consumers that might still hold 2130 * a reference to this clock. 2131 */ 2132 flags = clk_enable_lock(); 2133 clk->ops = &clk_nodrv_ops; 2134 clk_enable_unlock(flags); 2135 2136 if (!hlist_empty(&clk->children)) { 2137 struct clk *child; 2138 struct hlist_node *t; 2139 2140 /* Reparent all children to the orphan list. */ 2141 hlist_for_each_entry_safe(child, t, &clk->children, child_node) 2142 clk_set_parent(child, NULL); 2143 } 2144 2145 clk_debug_unregister(clk); 2146 2147 hlist_del_init(&clk->child_node); 2148 2149 if (clk->prepare_count) 2150 pr_warn("%s: unregistering prepared clock: %s\n", 2151 __func__, clk->name); 2152 2153 kref_put(&clk->ref, __clk_release); 2154 out: 2155 clk_prepare_unlock(); 2156 } 2157 EXPORT_SYMBOL_GPL(clk_unregister); 2158 2159 static void devm_clk_release(struct device *dev, void *res) 2160 { 2161 clk_unregister(*(struct clk **)res); 2162 } 2163 2164 /** 2165 * devm_clk_register - resource managed clk_register() 2166 * @dev: device that is registering this clock 2167 * @hw: link to hardware-specific clock data 2168 * 2169 * Managed clk_register(). Clocks returned from this function are 2170 * automatically clk_unregister()ed on driver detach. See clk_register() for 2171 * more information. 2172 */ 2173 struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw) 2174 { 2175 struct clk *clk; 2176 struct clk **clkp; 2177 2178 clkp = devres_alloc(devm_clk_release, sizeof(*clkp), GFP_KERNEL); 2179 if (!clkp) 2180 return ERR_PTR(-ENOMEM); 2181 2182 clk = clk_register(dev, hw); 2183 if (!IS_ERR(clk)) { 2184 *clkp = clk; 2185 devres_add(dev, clkp); 2186 } else { 2187 devres_free(clkp); 2188 } 2189 2190 return clk; 2191 } 2192 EXPORT_SYMBOL_GPL(devm_clk_register); 2193 2194 static int devm_clk_match(struct device *dev, void *res, void *data) 2195 { 2196 struct clk *c = res; 2197 if (WARN_ON(!c)) 2198 return 0; 2199 return c == data; 2200 } 2201 2202 /** 2203 * devm_clk_unregister - resource managed clk_unregister() 2204 * @clk: clock to unregister 2205 * 2206 * Deallocate a clock allocated with devm_clk_register(). Normally 2207 * this function will not need to be called and the resource management 2208 * code will ensure that the resource is freed. 2209 */ 2210 void devm_clk_unregister(struct device *dev, struct clk *clk) 2211 { 2212 WARN_ON(devres_release(dev, devm_clk_release, devm_clk_match, clk)); 2213 } 2214 EXPORT_SYMBOL_GPL(devm_clk_unregister); 2215 2216 /* 2217 * clkdev helpers 2218 */ 2219 int __clk_get(struct clk *clk) 2220 { 2221 if (clk) { 2222 if (!try_module_get(clk->owner)) 2223 return 0; 2224 2225 kref_get(&clk->ref); 2226 } 2227 return 1; 2228 } 2229 2230 void __clk_put(struct clk *clk) 2231 { 2232 if (!clk || WARN_ON_ONCE(IS_ERR(clk))) 2233 return; 2234 2235 clk_prepare_lock(); 2236 kref_put(&clk->ref, __clk_release); 2237 clk_prepare_unlock(); 2238 2239 module_put(clk->owner); 2240 } 2241 2242 /*** clk rate change notifiers ***/ 2243 2244 /** 2245 * clk_notifier_register - add a clk rate change notifier 2246 * @clk: struct clk * to watch 2247 * @nb: struct notifier_block * with callback info 2248 * 2249 * Request notification when clk's rate changes. This uses an SRCU 2250 * notifier because we want it to block and notifier unregistrations are 2251 * uncommon. The callbacks associated with the notifier must not 2252 * re-enter into the clk framework by calling any top-level clk APIs; 2253 * this will cause a nested prepare_lock mutex. 2254 * 2255 * In all notification cases cases (pre, post and abort rate change) the 2256 * original clock rate is passed to the callback via struct 2257 * clk_notifier_data.old_rate and the new frequency is passed via struct 2258 * clk_notifier_data.new_rate. 2259 * 2260 * clk_notifier_register() must be called from non-atomic context. 2261 * Returns -EINVAL if called with null arguments, -ENOMEM upon 2262 * allocation failure; otherwise, passes along the return value of 2263 * srcu_notifier_chain_register(). 2264 */ 2265 int clk_notifier_register(struct clk *clk, struct notifier_block *nb) 2266 { 2267 struct clk_notifier *cn; 2268 int ret = -ENOMEM; 2269 2270 if (!clk || !nb) 2271 return -EINVAL; 2272 2273 clk_prepare_lock(); 2274 2275 /* search the list of notifiers for this clk */ 2276 list_for_each_entry(cn, &clk_notifier_list, node) 2277 if (cn->clk == clk) 2278 break; 2279 2280 /* if clk wasn't in the notifier list, allocate new clk_notifier */ 2281 if (cn->clk != clk) { 2282 cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL); 2283 if (!cn) 2284 goto out; 2285 2286 cn->clk = clk; 2287 srcu_init_notifier_head(&cn->notifier_head); 2288 2289 list_add(&cn->node, &clk_notifier_list); 2290 } 2291 2292 ret = srcu_notifier_chain_register(&cn->notifier_head, nb); 2293 2294 clk->notifier_count++; 2295 2296 out: 2297 clk_prepare_unlock(); 2298 2299 return ret; 2300 } 2301 EXPORT_SYMBOL_GPL(clk_notifier_register); 2302 2303 /** 2304 * clk_notifier_unregister - remove a clk rate change notifier 2305 * @clk: struct clk * 2306 * @nb: struct notifier_block * with callback info 2307 * 2308 * Request no further notification for changes to 'clk' and frees memory 2309 * allocated in clk_notifier_register. 2310 * 2311 * Returns -EINVAL if called with null arguments; otherwise, passes 2312 * along the return value of srcu_notifier_chain_unregister(). 2313 */ 2314 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb) 2315 { 2316 struct clk_notifier *cn = NULL; 2317 int ret = -EINVAL; 2318 2319 if (!clk || !nb) 2320 return -EINVAL; 2321 2322 clk_prepare_lock(); 2323 2324 list_for_each_entry(cn, &clk_notifier_list, node) 2325 if (cn->clk == clk) 2326 break; 2327 2328 if (cn->clk == clk) { 2329 ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb); 2330 2331 clk->notifier_count--; 2332 2333 /* XXX the notifier code should handle this better */ 2334 if (!cn->notifier_head.head) { 2335 srcu_cleanup_notifier_head(&cn->notifier_head); 2336 list_del(&cn->node); 2337 kfree(cn); 2338 } 2339 2340 } else { 2341 ret = -ENOENT; 2342 } 2343 2344 clk_prepare_unlock(); 2345 2346 return ret; 2347 } 2348 EXPORT_SYMBOL_GPL(clk_notifier_unregister); 2349 2350 #ifdef CONFIG_OF 2351 /** 2352 * struct of_clk_provider - Clock provider registration structure 2353 * @link: Entry in global list of clock providers 2354 * @node: Pointer to device tree node of clock provider 2355 * @get: Get clock callback. Returns NULL or a struct clk for the 2356 * given clock specifier 2357 * @data: context pointer to be passed into @get callback 2358 */ 2359 struct of_clk_provider { 2360 struct list_head link; 2361 2362 struct device_node *node; 2363 struct clk *(*get)(struct of_phandle_args *clkspec, void *data); 2364 void *data; 2365 }; 2366 2367 static const struct of_device_id __clk_of_table_sentinel 2368 __used __section(__clk_of_table_end); 2369 2370 static LIST_HEAD(of_clk_providers); 2371 static DEFINE_MUTEX(of_clk_mutex); 2372 2373 /* of_clk_provider list locking helpers */ 2374 void of_clk_lock(void) 2375 { 2376 mutex_lock(&of_clk_mutex); 2377 } 2378 2379 void of_clk_unlock(void) 2380 { 2381 mutex_unlock(&of_clk_mutex); 2382 } 2383 2384 struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec, 2385 void *data) 2386 { 2387 return data; 2388 } 2389 EXPORT_SYMBOL_GPL(of_clk_src_simple_get); 2390 2391 struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data) 2392 { 2393 struct clk_onecell_data *clk_data = data; 2394 unsigned int idx = clkspec->args[0]; 2395 2396 if (idx >= clk_data->clk_num) { 2397 pr_err("%s: invalid clock index %d\n", __func__, idx); 2398 return ERR_PTR(-EINVAL); 2399 } 2400 2401 return clk_data->clks[idx]; 2402 } 2403 EXPORT_SYMBOL_GPL(of_clk_src_onecell_get); 2404 2405 /** 2406 * of_clk_add_provider() - Register a clock provider for a node 2407 * @np: Device node pointer associated with clock provider 2408 * @clk_src_get: callback for decoding clock 2409 * @data: context pointer for @clk_src_get callback. 2410 */ 2411 int of_clk_add_provider(struct device_node *np, 2412 struct clk *(*clk_src_get)(struct of_phandle_args *clkspec, 2413 void *data), 2414 void *data) 2415 { 2416 struct of_clk_provider *cp; 2417 2418 cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL); 2419 if (!cp) 2420 return -ENOMEM; 2421 2422 cp->node = of_node_get(np); 2423 cp->data = data; 2424 cp->get = clk_src_get; 2425 2426 mutex_lock(&of_clk_mutex); 2427 list_add(&cp->link, &of_clk_providers); 2428 mutex_unlock(&of_clk_mutex); 2429 pr_debug("Added clock from %s\n", np->full_name); 2430 2431 return 0; 2432 } 2433 EXPORT_SYMBOL_GPL(of_clk_add_provider); 2434 2435 /** 2436 * of_clk_del_provider() - Remove a previously registered clock provider 2437 * @np: Device node pointer associated with clock provider 2438 */ 2439 void of_clk_del_provider(struct device_node *np) 2440 { 2441 struct of_clk_provider *cp; 2442 2443 mutex_lock(&of_clk_mutex); 2444 list_for_each_entry(cp, &of_clk_providers, link) { 2445 if (cp->node == np) { 2446 list_del(&cp->link); 2447 of_node_put(cp->node); 2448 kfree(cp); 2449 break; 2450 } 2451 } 2452 mutex_unlock(&of_clk_mutex); 2453 } 2454 EXPORT_SYMBOL_GPL(of_clk_del_provider); 2455 2456 struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec) 2457 { 2458 struct of_clk_provider *provider; 2459 struct clk *clk = ERR_PTR(-EPROBE_DEFER); 2460 2461 /* Check if we have such a provider in our array */ 2462 list_for_each_entry(provider, &of_clk_providers, link) { 2463 if (provider->node == clkspec->np) 2464 clk = provider->get(clkspec, provider->data); 2465 if (!IS_ERR(clk)) 2466 break; 2467 } 2468 2469 return clk; 2470 } 2471 2472 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec) 2473 { 2474 struct clk *clk; 2475 2476 mutex_lock(&of_clk_mutex); 2477 clk = __of_clk_get_from_provider(clkspec); 2478 mutex_unlock(&of_clk_mutex); 2479 2480 return clk; 2481 } 2482 2483 int of_clk_get_parent_count(struct device_node *np) 2484 { 2485 return of_count_phandle_with_args(np, "clocks", "#clock-cells"); 2486 } 2487 EXPORT_SYMBOL_GPL(of_clk_get_parent_count); 2488 2489 const char *of_clk_get_parent_name(struct device_node *np, int index) 2490 { 2491 struct of_phandle_args clkspec; 2492 struct property *prop; 2493 const char *clk_name; 2494 const __be32 *vp; 2495 u32 pv; 2496 int rc; 2497 int count; 2498 2499 if (index < 0) 2500 return NULL; 2501 2502 rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index, 2503 &clkspec); 2504 if (rc) 2505 return NULL; 2506 2507 index = clkspec.args_count ? clkspec.args[0] : 0; 2508 count = 0; 2509 2510 /* if there is an indices property, use it to transfer the index 2511 * specified into an array offset for the clock-output-names property. 2512 */ 2513 of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) { 2514 if (index == pv) { 2515 index = count; 2516 break; 2517 } 2518 count++; 2519 } 2520 2521 if (of_property_read_string_index(clkspec.np, "clock-output-names", 2522 index, 2523 &clk_name) < 0) 2524 clk_name = clkspec.np->name; 2525 2526 of_node_put(clkspec.np); 2527 return clk_name; 2528 } 2529 EXPORT_SYMBOL_GPL(of_clk_get_parent_name); 2530 2531 struct clock_provider { 2532 of_clk_init_cb_t clk_init_cb; 2533 struct device_node *np; 2534 struct list_head node; 2535 }; 2536 2537 static LIST_HEAD(clk_provider_list); 2538 2539 /* 2540 * This function looks for a parent clock. If there is one, then it 2541 * checks that the provider for this parent clock was initialized, in 2542 * this case the parent clock will be ready. 2543 */ 2544 static int parent_ready(struct device_node *np) 2545 { 2546 int i = 0; 2547 2548 while (true) { 2549 struct clk *clk = of_clk_get(np, i); 2550 2551 /* this parent is ready we can check the next one */ 2552 if (!IS_ERR(clk)) { 2553 clk_put(clk); 2554 i++; 2555 continue; 2556 } 2557 2558 /* at least one parent is not ready, we exit now */ 2559 if (PTR_ERR(clk) == -EPROBE_DEFER) 2560 return 0; 2561 2562 /* 2563 * Here we make assumption that the device tree is 2564 * written correctly. So an error means that there is 2565 * no more parent. As we didn't exit yet, then the 2566 * previous parent are ready. If there is no clock 2567 * parent, no need to wait for them, then we can 2568 * consider their absence as being ready 2569 */ 2570 return 1; 2571 } 2572 } 2573 2574 /** 2575 * of_clk_init() - Scan and init clock providers from the DT 2576 * @matches: array of compatible values and init functions for providers. 2577 * 2578 * This function scans the device tree for matching clock providers 2579 * and calls their initialization functions. It also does it by trying 2580 * to follow the dependencies. 2581 */ 2582 void __init of_clk_init(const struct of_device_id *matches) 2583 { 2584 const struct of_device_id *match; 2585 struct device_node *np; 2586 struct clock_provider *clk_provider, *next; 2587 bool is_init_done; 2588 bool force = false; 2589 2590 if (!matches) 2591 matches = &__clk_of_table; 2592 2593 /* First prepare the list of the clocks providers */ 2594 for_each_matching_node_and_match(np, matches, &match) { 2595 struct clock_provider *parent = 2596 kzalloc(sizeof(struct clock_provider), GFP_KERNEL); 2597 2598 parent->clk_init_cb = match->data; 2599 parent->np = np; 2600 list_add_tail(&parent->node, &clk_provider_list); 2601 } 2602 2603 while (!list_empty(&clk_provider_list)) { 2604 is_init_done = false; 2605 list_for_each_entry_safe(clk_provider, next, 2606 &clk_provider_list, node) { 2607 if (force || parent_ready(clk_provider->np)) { 2608 clk_provider->clk_init_cb(clk_provider->np); 2609 list_del(&clk_provider->node); 2610 kfree(clk_provider); 2611 is_init_done = true; 2612 } 2613 } 2614 2615 /* 2616 * We didn't manage to initialize any of the 2617 * remaining providers during the last loop, so now we 2618 * initialize all the remaining ones unconditionally 2619 * in case the clock parent was not mandatory 2620 */ 2621 if (!is_init_done) 2622 force = true; 2623 2624 } 2625 } 2626 #endif 2627